Vocal behavior of the Mountain Hawk-Eagle Nisaetus nipalensis in Taiwan

Abstract

The Mountain Hawk-Eagles (Nisaetus nipalensis) is a large raptor native to Asia. Despite the wide distribution of this species, their vocalizations have been described only occasionally, and no studies have provided detailed outcomes for other researchers to follow. This study aimed to obtain systematic and comprehensive results on the vocalizations of the Mountain Hawk-Eagle and a preliminary understanding of its vocal behavior in terms of temporal changes. This study performed a road transect survey along two forestry roads between January 2006 and December 2008 in Taitung County. Two nests were found and observed upstream of the Dazhu and Fangshan streams during the breeding season in 2007 and 2010, respectively. All vocalizations, vocal behavior, and behavior context were recorded. Mountain Hawk-Eagles were discovered to produce at least seven types of vocalization depending on context and structure. The flying call was recorded throughout the year and was made by both sexes. Some vocalizations were recorded only during the breeding season or could only be identified around the nest area; for example, the female begging call, juvenile begging call, and alarm call. From the road transect survey and observation of nests during breeding seasons, we discovered temporal variation in the call rate of the Mountain Hawk-Eagle. The findings and recordings made in this study provide insight into the vocal behavior of the Mountain Hawk-Eagle, but further investigations are needed.